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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let cj=prompt("请输入成绩:")
        if(cj>90){
            alert('优秀')
        }
        else if(cj>=70&&cj<90){
            alert('良好')
        }
        else if (cj>=60&&cj<70){
            alert('及格')
        }
        else  {
            alert('及格')
        }
    </script>
</body>
</html>